Fuel systems for internal combustion engines and, in particular, diesel, gasoline and turbine engines have a high pressure fuel pump which is actuated in timed relationship to deliver fuel under pressure to the combustion spaces of the engine. Examples are new generations of electrically-controlled diesel engines which have unit injectors and gasoline engines with injectors located at either the throttle body or at the individual cylinders. Air and fuel vapor can cause malfunctions or "vapor lock" in these systems and prevent proper metering of fuel for injection and proper combustion. The emerging new diesel and gasoline/gasohol engines which utilize injectors operate with an excess of fuel which is returned to fuel tanks, tending to create pressure pulsations as they open and close during normal operation. When a flowing liquid is suddenly stopped, interrupted or exposed to certain valving action a pressure wave is created since the fluid is not sufficiently elastic to absorb the energy or pressure waves or pulsations created in the fluid. The pulsations travel back through the incoming column of fuel to the fuel pump and other components such as sensors where the pulsations may cause fatigue damage, decrease the efficiency of the fuel pump and harm valves, gaskets, fasteners, sensors and other fuel system components.
It is therefore desirable to provide a method for such systems which will reduce the magnitude of the pressure pulsations caused by the sudden closing of valves or injectors with the abrupt halting of moving fluid, which will also automatically function to purge any entrained air, gas or vapor from the fluid which is flowing through the system between the fuel pump and the internal combustion engine. It would also be desirable to provide such a system which would function to check excessive back flow or siphoning of fluids without the need of a valve having moving parts which requires close tolerance surfaces and that may create a restriction to the fluid flow in the system as would be typical when using a check valve with weights or springs.